The present invention is in the field of tribology and specifically for reduction of frictional coefficient and wear on metal surfaces. The frictional force and wear are general phenomena for any machine and device under operational condition it reduces the efficiency and life of the machine whereas lubricants reduce the frictional resistance and wear of machine or device and increase their life and efficiency. However, many lubricants have their limited ability to perform under high load and sliding speed of machine or device. Aqueous lubricant composition has many advantages over oil as lubricants it can serve coolant to the sliding surface along with ecological and economic advantages. It has disadvantage of low pressure coefficient of viscosity, which decreases the ability to support high load. The prior art, Plaza S et al.; WEAR 249(12):1077-89(2001) describes a polyoxyethylenediphosphate derivative that appears to show some antiwear and friction reduction activity in aqueous solution. At a load 5N, all sample tested showed friction coefficient around 0.1. Lei H et al.; WEAR, 252(3-4):345-50(2002) describes a fullerene-styrene sufonicacid copolymer, which shows low (0.3) friction coefficient at the lowest loads which is reported at 100N. The wear scar is shown to be very sulfur rich after wear test. Duan B and Lei H, WEAR, 249(5-6); 528-32(2001) report the use of colloidal polystyrene as an additive to aqueous fluids such as triethanolamine aqueous solution and a water soluble zincalkoxyphosphate (OPZ) solution which showed the addition of colloidal polystyrene in this combination the base fluid appears to have a beneficial effect on the wear behavior of steel, as demonstrated by the maximum non-seizure load. However, the wear scar diameter did not reduce in comparison with colloid free solution. There was no mention of friction reduction behavior.
In the prior art, several patents disclosed the use of different polymer and copolymers in aqueous lubricants along with other components such as block copolymer of polyoxyethylene-polyoxypropylene (U.S. Pat. No. 4,452,712) about 0.1-20 wt % of water soluble mixture along with 0.5-10 wt % of water soluble alkanolamine to provide metal working lubricant to improve friction and corrosion inhibition ability. Again in patent (EP 0059461) discloses water based hydraulic fluids incorporating a polyether as a lubricant and corrosion inhibitor. (U.S. Pat. No. 4,828,735) discloses the aqueous composition of polyether along with polyamide component having suitable formulation for use as a hydraulic fluid, metal drawing fluid and aqueous cutting fluid.
The closest prior art is U.S. Pat. No. 7,514,150 B2. This patent has disclosed a copolymerization of polyionic backbone along with poly L-lysin and other similar molecules for polymerization with an objective of mixing it with aqueous medium as an additive.
Therefore, it is an object of the invention to provide a stable polymeric material that can be added easily and cost effectively to an aqueous medium to produce aqueous lubricant which can be used effectively to reduce friction and wear substantially. There are several important physical properties which are used to characterize the friction coefficient and wear for industrial aqueous lubricant. Some of the important methods are given below for better understanding of present invention.
Friction and wear properties were evaluated on a four ball test rig. The tests were conducted using standard 12.7 mm diameter EN31 steel balls, rotation speed of 1200 rpm, 196.2 N load, temperature of 54° C. and test duration of 60 minutes. The coefficient of friction was monitored throughout the test duration and wear scar diameter of the balls were measured at the end of the test.
EP properties of the lubricating additive were evaluated in a standard four ball m/c as per IP-239 test method.
The present invention is significantly different from prior art patents as described above for use of vinyl group containing polyhydric alcohol as comonomer for making aqueous lubricant additive.